'91 K5 Four Wheel Camper

[ZooMad75]

Yeah this week sucked as far as progress goes. Thank goodness I was able to secure the prop valve and lines from the local yard. Looking at work and online NOBODY sells that stupid valve for the 90-91 RWAL systems. Even more thanks for Larry's smart thinking to figure a way to retro-grade the unobtainable ABS system out of the truck and get back to stone simple reliable basic non-abs brakes. That being said, look out for a complete ABS module and dump valve going up on Craigslist.

The transfer case is getting it's operation tomorrow at work. So by the afternoon we can get back on track.

 

[tRustyK5]

I pitched the RWAL system on my 90 Blazer too. Much cleaner and simpler...and the RWAL wasn't working on my truck anyways.

 

[ZooMad75]

Autopsy on the original 241 was about as bad as it could get. Lots of debris in the case, clogged pump pickup and metal on the magnet. The input was about the only thing reusable in the case. Even then we swapped the input bearing and low range planetary gear set from the 32 spline input onto the 27 spline input. The dog teeth were a little rounded, but useable. Pics coming tonight.

 

[ZooMad75]

So the transfer case is done. As expected the one we pulled out was beyond junk. Lots of metal on the magnet and more crap clogging the pump pickup.



It's just nasty inside.


Pile-o-junk. Nothing here is worth reusing. Bearings are rough to spin and the chain is stretched.


So here's the only sore spot. Shown below is the dog teeth for the low range gear, this is on the 27 spline input. This has to be reused so it will couple up to the trans. It's not as clean as what the 32 spline teeth are, but it's what I'm going to run.


Inside the 2nd t-case. The blue RTV says somebody has been here recently. Shift fork pads were all complete and in place. We did replace the 4 short ones as they were brittle, but the two blue long pads were just fine. Chain is nice too. No crap anywhere inside the case.


A mainshaft that isn't bent. Amazing.


Brakes are still being a pain. Larry and I thought it would take a short time to bleed now with the ABS out and it turned into a full afternoon of banging our head on the truck. No flow to the rear. Need to regroup.

I did bring the DRAC module home to recalibrate it for the axle ratio change and bigger tires.
__________________

 

[tRustyK5]

There is a button on the new combo/prop valve you installed. It needs to be depressed in some way or another to recenter the mechanism inside. Something I also need to do. I think it needs to be held in while someone pushes the brake pedal.

 

[ZooMad75]

There is a button on the new combo/prop valve you installed. It needs to be depressed in some way or another to recenter the mechanism inside. Something I also need to do. I think it needs to be held in while someone pushes the brake pedal.

Yeah that was done. We even constructed a "L" shaped bracket to bolt onto the prop valve and hold it in as illustrated in the 91 R/V service manual. No dice. Ian showed up to borrow a tool from me and we put him to work on the bleeder while I pumped and Larry held the button in on the prop valve. We tried every combination you can think of. Except vacuum or pressure bleeding.

 

[ZooMad75]

I got a little bit done this morning. I went ahead and made the changes needed to have the Drac module read correctly with the tire size and gearing we have. I used the info found on this page https://harristuning.com/Tbi/vssb-drac-calibration/ which was very helpful.

Here's the Drac module.


Here it is opened up. The straight jumpers are what need to be altered, here it is before.


Here it is after. I had to remove one jumper and add 3 more in different spots. We'll see if it's accurate or not!

__________________

 

[campfire]

I got a little bit done this morning. I went ahead and made the changes needed to have the Drac module read correctly with the tire size and gearing we have. I used the info found on this page http://tbichips.com/drac/ which was very helpful.

Here's the Drac module.


Here it is opened up. The straight jumpers are what need to be altered, here it is before.

Here it is after. I had to remove one jumper and add 3 more in different spots. We'll see if it's accurate or not!

__________________

Any reason you didn't upgrade to a switch block (so you can adjust the configuration without having to re-solder the jumpers)?

I'm thinking of how it was done in this thread.

 

[ZooMad75]

Thought about using dip switches. No place local to buy any since Radio Shack went belly up. No major plans to change tire size or axle ratio anytime soon. Even if I want to, it's 30 seconds to pull it out from the dash and 10 minutes to change the jumpers.

 

[campfire]

Thought about using dip switches. No place local to buy any since Radio Shack went belly up. No major plans to change tire size or axle ratio anytime soon. Even if I want to, it's 30 seconds to pull it out from the dash and 10 minutes to change the jumpers.

Ok.

 

[ZooMad75]

Small progress report. Larry's kicking ass with the wiring. I swear he is getting better with every truck he's done. The wiring is turning out way cleaner and neatly routed than any UAW guy back in the day would have ever done. No pics as I'll let him take better shots than ones from a cell phone. It's just very tidy and tucked away blending into the background letting the engine be the focal point under the hood. He's got fresh battery cables and money for some fuel I dropped off tonight, so getting this thing lit off isn't far from happening. He's got more wiring to do, but should be done soon. Getting exciting.

 

[y5mgisi]

Bleeding brakes is pretty much always Lame.

 

[Larry]

Wiring updates…

As with the Polar Bear 8.1L swap, I had to dig deep into the harness hord for GM proper connectors and wire colors/size to keep the wiring GM logical. Any dumchit that knows GM logic could work on this rig 25 years down the road.

Bulk head wiring done. Working my way to the ECM and Fuel Pump relay

Got the MEFI-4 ECM mounted snugly under the dash. MEFI ECM’s are funny in that there are only a 2 power wires (key on and constant hot) but there are tons of grounds. I found it cleaner and easier to create a ground junction block on the ECM mounting bracket in an effort to clean up the engine bay of all the ugly grounds. There is a huge ground cable going from this junction block to the transmission bolt/stud then another going from the mounting bracket to the body. Seems like a good grounding solution. We’ll see! Also labeled everything for ease of service down the road.

Further back shot. I test fitted the glove box to make sure the door swing would clear the ECM. Passed with flying colors and the ECM is easy to access.

This is where I ended tonight. I plan on leaving this much exposed until after the initial fire up to make sure everything is wired correctly. The only thing left to wire up is the coolant temp sender and fuel pump. Might be able to crank this beeotch up before Thanksgiving after all! Oh, yeah... still need to rig up the throttle cable stuff and 700R4 TV cable dealeo.

 

[y5mgisi]

Good stuff! Just curious as to why you guys went with that ecm instead of the standard 0411?

 

[Larry]

Good stuff! Just curious as to why you guys went with that ecm instead of the standard 0411?

Because a bird in hand is worth more than two in the bush. I had a MEFI-4 ECM and harness in stock. Plus, it really makes for a clean install. MEFI can be a hassle to program but with this K5 being an auto trans it should be much less of a hassle than it was to program the 8.1L w/manual trans when I had this on my K10. I just hope the laptop I have the MEFI tuning software still works.....I haven't turned it on in a couple years

 

[y5mgisi]

Gotcha. Shouldn't be bad but I guess worst case scenario, it wouldn't really be the worst thing ever to have to put a new ls harness and ecm in if it does end up giving you fits.

 

[ZooMad75]

Keep in mind the MEFI4 controller is used in a number of applications beyond the Ramjet crate engines that the started out coming from. Turnkey engine uses them for their crate engine packages and Painless Wiring's EFI kit uses the same controller. Not to mention all the boat applications the system was born from. Like Larry said the install is SO much cleaner. I'll get to cut my teeth on tuning with the old laptop too. Got to do some research on that so I don't melt it down!

 

[ZooMad75]

Larry is getting into the zone now. Wiring used to be something he dreaded but now after doing 4 trucks with complete powertrain change overs he's really good at it now. Using GM schematics will help troubleshooting if something does go wrong later. He's had no trouble on any of his other builds so I'm pretty confident this will be no different.

I did drop off some more goodies on Saturday after work. One of which was a coolant temp sensor needed for the gauge to work. There was some back and forth discussion on this subject Friday. The stock gauge uses a single wire sender that is just providing a resistance to ground for the gauge to work. The stock 5.3 sensors (which we have 2, one for the gauge and one for the ECM) use a 2 wire hookup. Reviewing the factory schematics for the 5.3 the ground is just returned back to the ECM. Now we could have used this with the right connector and ground the 2nd wire. The question was if the resistance values were the same from the old to the new for gauge accuracy. Next option was surfing the web and finding a conversion sensor on ebay or elsewhere. No time for that option as Larry needs it to be able to fill the cooling system soon. Web surfing found two more options, drill the head to a larger hole for the 3/8 npt pipe fitting needed for the 91 gauge sender or machine down the 91 sensor to the 12m x 1.5 metric hole that the head has.

Talking with my ace tech at work about it, knowing he's got a metalworking lathe we hatched a plan. Now he as well as Larry was skeptical about machining the sensor down, but after what I had found online this had been done many times with good success. I ordered a new sensor from Napa and handed off to my tech to take home Friday night. Later on he sent me a text with the finished product. Seen Here:



Larry threaded it in Sat and found the correct single wire connector to hook it up with. So to all LS swapper's out there, you can use your factory gauges with your swap. We are using a stock 5.3 oil pressure sensor, just like Larry did with the 8.1's in his and with one minor adjustment, the stock coolant temp sensor too. The ECM doesn't need to see an oil psi signal and since each head has a hole for a coolant sensor, the drivers side will get the ecm sensor and the pass side gets the gauge sensor.

Looking at Larry's work on the wiring is just beyond words. As his pics show everything is neat and tidy and using GM logic every step of the way. We are a couple of wire hookups and topping off fluids away from hitting the ignition.

 

[y5mgisi]

Very exciting!

 

[campfire]

Larry is getting into the zone now. Wiring used to be something he dreaded but now after doing 4 trucks with complete powertrain change overs he's really good at it now. Using GM schematics will help troubleshooting if something does go wrong later. He's had no trouble on any of his other builds so I'm pretty confident this will be no different.

I did drop off some more goodies on Saturday after work. One of which was a coolant temp sensor needed for the gauge to work. There was some back and forth discussion on this subject Friday. The stock gauge uses a single wire sender that is just providing a resistance to ground for the gauge to work. The stock 5.3 sensors (which we have 2, one for the gauge and one for the ECM) use a 2 wire hookup. Reviewing the factory schematics for the 5.3 the ground is just returned back to the ECM. Now we could have used this with the right connector and ground the 2nd wire. The question was if the resistance values were the same from the old to the new for gauge accuracy. Next option was surfing the web and finding a conversion sensor on ebay or elsewhere. No time for that option as Larry needs it to be able to fill the cooling system soon. Web surfing found two more options, drill the head to a larger hole for the 3/8 npt pipe fitting needed for the 91 gauge sender or machine down the 91 sensor to the 12m x 1.5 metric hole that the head has.

Talking with my ace tech at work about it, knowing he's got a metalworking lathe we hatched a plan. Now he as well as Larry was skeptical about machining the sensor down, but after what I had found online this had been done many times with good success. I ordered a new sensor from Napa and handed off to my tech to take home Friday night. Later on he sent me a text with the finished product. Seen Here:



Larry threaded it in Sat and found the correct single wire connector to hook it up with. So to all LS swapper's out there, you can use your factory gauges with your swap. We are using a stock 5.3 oil pressure sensor, just like Larry did with the 8.1's in his and with one minor adjustment, the stock coolant temp sensor too. The ECM doesn't need to see an oil psi signal and since each head has a hole for a coolant sensor, the drivers side will get the ecm sensor and the pass side gets the gauge sensor.

Looking at Larry's work on the wiring is just beyond words. As his pics show everything is neat and tidy and using GM logic every step of the way. We are a couple of wire hookups and topping off fluids away from hitting the ignition.

Awesome!